Novel propylene polymerization process

Abstract

A novel process for the production of substantially amorphous interpolymers of propylene, ethylene and optionally a third alpha-olefin comonomer having between 4 and 8 carbon atoms per molecule is disclosed. The polymers have properties which make them applicable for use, e.g., as hot melt adhesives and as blending components in roofing materials.

What is claimed is: 
     
       1. A process for the production of substantially amorphous interpolymers which comprises polymerizing from about 70 to about 90 wt. % propylene and from about 10 to about 30 wt. % ethylene at a temperature between about 130° F. and about 175° F. and at a reactor pressure sufficient to maintain propylene in the liquid phase, in the presence of from about 0.7 to about 3.0 mol % hydrogen based on the monomer feed to the process and employing as catalyst a composition comprised of: (a) a solid catalyst component produced by the method comprising (i) co-communicating magnesium halide support base and aluminum trihalide in a molar ratio from about 8:0.5 to about 8:3 in the absence of added electron donor and (ii) then co-communicating the product of step (i) in the absence of added electron donor with sufficient titanium tetrahalide to provide a molar ratio of magnesium halide to titanium tetrahalide from about 8:0.4 to about 8:1; and     (b) a co-catalyst component comprised of a mixture of from about 15 to about 90 mol % of trialkylaluminum having from 1 to 9 carbon atoms in each alkyl group and about 85 to about 10 mol % of an alkylaluminum halide having at least one halide group per molecular in a sufficient quantity to provide an Al/Ti ratio in the range from about 50:1 to about 600:1; and recovering a substantially amorphous, random interpolymer having a tacticity index m/r ranging between about 3 and about 4 as determined by 13C NMR spectra.     
     
     
       2. The process of claim 1 wherein each halide is a chloride, each alkyl is an ethyl group and the alkylaluminum halide is diethylaluminum chloride. 
     
     
       3. The process of claim 2 wherein said pressure is between about 400 psig and about 550 psig and the temperature is between about 150° F. and 160° F. 
     
     
       4. The process of claim 1 wherein said magnesium halide to aluminum trihalide ratio ranges from about 8 1 to about 8:1.5. 
     
     
       5. The process of claim 1 wherein said magnesium halide to titanium tetrahalide molar ratio ranges from about 8:0.4 to about 8:0.6. 
     
     
       6. The process of claim 2 wherein the triethylaluminum content of the co-catalyst mixture ranges between about 40 and about 60 mol %. 
     
     
       7. The process of claim 2 wherein the Al/Ti ratio is maintained between about 90:1 and about 300:1. 
     
     
       8. The process of claim 2 wherein the hydrogen is maintained between about 1.2 and about 2.5 mol % based on the total monomer feed to the process. 
     
     
       9. The process of claim 2 carried out under continuous conditions at an average residence time between about 1 hour and about 3 hours. 
     
     
       10. The process of claim 2 wherein the solids content of the reactor slurry is maintained between about 30 wt % and about 60 wt %.